A Jfet to use for switching?
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From: Paul E. Schoen on 10 Feb 2010 02:16 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:egg4n5hfi2ln5agh1naofpgnfqbjr74s0r(a)4ax.com... > On Tue, 09 Feb 2010 23:44:20 -0500, Bitrex > <bitrex(a)de.lete.earthlink.net> wrote: > >>John Larkin wrote: >>> On Tue, 09 Feb 2010 19:46:38 -0500, Bitrex >>> <bitrex(a)de.lete.earthlink.net> wrote: >>> >>>> Can anyone recommend an N channel TO-92 JFET that would be good for >>>> signal switching in a battery powered application? The on resistance >>>> isn't really critical, but the supply voltage and the signal amplitude >>>> require that the pinchoff voltage always be less than -2 volts or so. >>> >>> No chance of using an integrated CMOS analog switch? >>> >>> John >>> >> >>I only need one switch, and as a hobbyist doing a prototype on >>breadboard I was hoping to use through-hole components. All the single >>switch CMOS ICs I've seen have been in surface-mount packages. I >>suppose if I have to I can overcome the aesthetic objections of using >>something like a 4066 for this application. > > There are some cute, cheap single-gate CMOS switches, but they're > SOT-23s or smaller. You can also use a MOSFET output optocoupler in a 6-pin DIP. Here are some from NEC: http://www.necel.com/opto/en/ocmos.html But you probably need a JFET for bidirectional analog switching. Try an H11F1M: http://www.fairchildsemi.com/pf/H1/H11F1M.html And for higher voltage (400V) try: http://www.newark.com/jsp/search/altsSubs.jsp?type=alts&sku=06C0527 Paul
From: Fred Bartoli on 10 Feb 2010 05:09 Bitrex a �crit : > John Larkin wrote: >> On Tue, 09 Feb 2010 19:46:38 -0500, Bitrex >> <bitrex(a)de.lete.earthlink.net> wrote: >> >>> Can anyone recommend an N channel TO-92 JFET that would be good for >>> signal switching in a battery powered application? The on resistance >>> isn't really critical, but the supply voltage and the signal >>> amplitude require that the pinchoff voltage always be less than -2 >>> volts or so. >> >> No chance of using an integrated CMOS analog switch? >> >> John >> > > I only need one switch, and as a hobbyist doing a prototype on > breadboard I was hoping to use through-hole components. All the single > switch CMOS ICs I've seen have been in surface-mount packages. I > suppose if I have to I can overcome the aesthetic objections of using > something like a 4066 for this application. Try Vishay J201/SST201 or Fairchild J201/MMBF201 -- Thanks, Fred.
From: John Larkin on 10 Feb 2010 10:18 On Wed, 10 Feb 2010 02:16:24 -0500, "Paul E. Schoen" <paul(a)peschoen.com> wrote: > >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:egg4n5hfi2ln5agh1naofpgnfqbjr74s0r(a)4ax.com... >> On Tue, 09 Feb 2010 23:44:20 -0500, Bitrex >> <bitrex(a)de.lete.earthlink.net> wrote: >> >>>John Larkin wrote: >>>> On Tue, 09 Feb 2010 19:46:38 -0500, Bitrex >>>> <bitrex(a)de.lete.earthlink.net> wrote: >>>> >>>>> Can anyone recommend an N channel TO-92 JFET that would be good for >>>>> signal switching in a battery powered application? The on resistance >>>>> isn't really critical, but the supply voltage and the signal amplitude >>>>> require that the pinchoff voltage always be less than -2 volts or so. >>>> >>>> No chance of using an integrated CMOS analog switch? >>>> >>>> John >>>> >>> >>>I only need one switch, and as a hobbyist doing a prototype on >>>breadboard I was hoping to use through-hole components. All the single >>>switch CMOS ICs I've seen have been in surface-mount packages. I >>>suppose if I have to I can overcome the aesthetic objections of using >>>something like a 4066 for this application. >> >> There are some cute, cheap single-gate CMOS switches, but they're >> SOT-23s or smaller. > >You can also use a MOSFET output optocoupler in a 6-pin DIP. Here are some >from NEC: >http://www.necel.com/opto/en/ocmos.html > >But you probably need a JFET for bidirectional analog switching. Try an >H11F1M: >http://www.fairchildsemi.com/pf/H1/H11F1M.html > >And for higher voltage (400V) try: >http://www.newark.com/jsp/search/altsSubs.jsp?type=alts&sku=06C0527 > >Paul > > I've used bidirectional mosfet SSRs as analog switches and they work fine. They are available in dip and surface mount. NEC PS7141-1A is one we use like this. It will switch 400 volts! Offset voltages on these things is zero. John
From: Joerg on 10 Feb 2010 13:08 Bitrex wrote: > John Larkin wrote: >> On Tue, 09 Feb 2010 19:46:38 -0500, Bitrex >> <bitrex(a)de.lete.earthlink.net> wrote: >> >>> Can anyone recommend an N channel TO-92 JFET that would be good for >>> signal switching in a battery powered application? The on resistance >>> isn't really critical, but the supply voltage and the signal >>> amplitude require that the pinchoff voltage always be less than -2 >>> volts or so. >> >> No chance of using an integrated CMOS analog switch? >> >> John >> > > I only need one switch, and as a hobbyist doing a prototype on > breadboard I was hoping to use through-hole components. ... You really should try to overcome that limitation. If you shun SOT23 devices you are going to be missing out on a world of new and wonderful devices. BF862 and such. http://www.nxp.com/documents/data_sheet/BF862.pdf [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Bitrex on 10 Feb 2010 23:30 Fred Bartoli wrote: > Bitrex a �crit : >> John Larkin wrote: >>> On Tue, 09 Feb 2010 19:46:38 -0500, Bitrex >>> <bitrex(a)de.lete.earthlink.net> wrote: >>> >>>> Can anyone recommend an N channel TO-92 JFET that would be good for >>>> signal switching in a battery powered application? The on >>>> resistance isn't really critical, but the supply voltage and the >>>> signal amplitude require that the pinchoff voltage always be less >>>> than -2 volts or so. >>> >>> No chance of using an integrated CMOS analog switch? >>> >>> John >>> >> >> I only need one switch, and as a hobbyist doing a prototype on >> breadboard I was hoping to use through-hole components. All the >> single switch CMOS ICs I've seen have been in surface-mount packages. >> I suppose if I have to I can overcome the aesthetic objections of >> using something like a 4066 for this application. > > Try Vishay J201/SST201 or Fairchild J201/MMBF201 > > > Looking at the datasheet, I think this device will work nicely in my application.
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